It is well understood that the greater the vaporization or gasification of liquid fuel that can be accomplished the greater the surface area of the fuel which is subject to oxidation and therefore the higher the rate of combustion. In other words, the greater the percentage of the fuel that can be burned, the more efficient the operation of the engine. Attempts to completely gasify liquid hydrocarbon fuel go back many years. However, all of these attempts have had significant shortcomings. In some instances, the devices did not completely vaporize the fuel and therefore the expected increase in efficiency did not materialize. In other cases, the devices were of such a complex nature as to negate any real benefit from them or require such high power inputs themselves that even though a greater fuel efficiency was realized, the increased power needs negated this benefit.
It is elementary that in order to maximize the combustion of fuels it is necessary to bring as much of that fuel as possible into close proximity with oxygen. The only portion of a droplet of fuel which can be oxidized is the surface area. Therefore, the smaller the droplets the greater the total percentage of fuel which can be burned or oxidized. Thus, to increase oxidation it is necessary to increase vaporization. All present commercially successful carburetion systems attempt to vaporize liquid fuel prior to introduction into the manifold of the engine. While this is possible to some extent, the variation in fuel droplet size at the intakes to the carburetor can vary substantially and in fact a relatively low percentage of the total fuel is actually oxidized and burned when supplied through a standard carburetor.
The ultimate carburetion system would be one that feeds fuel to the manifold in a pre-vaporized or gaseous form and particularly one in which all liquid fuel is converted to a gaseous fuel prior to entering the manifold and the cylinders of the engine. The known prior art devices have fallen short in several respects in accomplishing this end.
For instance, one of the most noted prior art devices which was developed by Charles Nelson Pogue in the 1930's was a carburetor for the vaporization of gasoline which has been widely advertised as the two hundred mile per gallon carburetor. This device has never enjoyed wide commercial success because it is nearly as large and cumbersome as the engine it is meant to fuel and it requires an operating temperature which approaches the flash point of fuel, such as gasoline. Therefore, the safety of the passengers in the vehicle in which the carburetor is used may be in jeopardy as well as those who are near the vehicle. In other words, the potential for an explosion is quite great.
A device for vaporizing fuel, such as diesel fuel is disclosed in U.S. Pat. No. 1,806,581 to Bethenod for "Fuel Supply System For Internal Combustion Engines of Variable Load For Using Heavy Fuels." The diesel fuel is supplied through a conventional gasoline carburetor and air is drawn through an intake by means of a vacuum pump. This system is an open system, i.e., air in large quantities is continuously drawn in from the atmosphere by a first vacuum pump. A second vacuum pump is intended to pull a vacuum on the air-fuel mixture in a reservoir to vaporize the fuel whereupon it is fed into a manifold of an engine which is supplied with still an additional air intake. Heat exchange means are provided around the reservoir and again near the intake manifold to minimize fluctuations in fuel temperature. Because the system is open, large quantities of air are drawn through it making it very difficult to draw a sufficient vacuum to substantially vaporize any fuel which was not vaporized directly by the carburetor. In other words, for such a device to operate effectively it would be necessary to provide such a huge vacuum pump that the fuel savings, if any, would be negligible. Alternatively, with a smaller vacuum pump the fuel is not properly vaporized in an open system wherein atmospheric air is constantly being drawn into the system.
Another device for providing gaseous fuel to the carburetor of an internal combustion engine is shown in U.S. Pat. No. 3,630,698 to Joseph H. Baldwin for "Fuel System". In this device, gaseous vapors are drawn from a vacuum chamber by means of a manifold vacuum. The vacuum chamber contains a supply of liquid fuel which is replenished through a float valve. Two potential problems are associated with this type of device. First, the vacuum from the manifold may not be sufficient under certain load conditions to provide sufficient fuel to the engine. Second, by drawing the gaseous vapors off a body of liquid gasoline the lighter hydrocarbons are boiled off first, leaving a relatively heavy liquid hydrocarbon, frequently referred to as "strip oil". Therefore, in order to keep the system working properly, means must be provided to regularly withdraw the strip oil and replace it with fresh gasoline.
Another device for vaporizing gasoline is disclosed in U.S. Pat. No. 4,040,403 to Rose, et al. for "Air-Fuel Mixture Control System". In this device, fuel is supplied to a vaporizer wherein the level of the liquid fuel in the vaporizer is controlled by a float valve. Hot exhaust gases from the engine are boiled through the liquid gasoline causing a portion of it to be vaporized and carried to the engine. The device includes a complex amplifying system for adjusting the air-fuel mixture and a separator for taking out any fuel droplets from the fuel as it is vaporized in the vaporizer. With this device, the lighter hydrocarbons will be vaporized leaving behind the heavier hydrocarbons or strip oil.
U.S. Pat. No. 4,175,525 to Johnson for "Fuel Vaporizer System For Internal Combustion Engines" discloses a sealed vaporization system connected between a fuel supply line and the intake manifold of an internal combustion engine and operated in parallel with a carburetor. A float valve is provided in this device to control the flow of liquid fuel to a chamber wherein it is vaporized and fed to a carburetor. The lighter hydrocarbons will be boiled off of the liquid fuel before the heavier hydrocarbons leaving strip oil in the chamber.
Another difficulty with prior art devices utilized to vaporize fuel is that no adequate provision has been provided for lubricating the walls of the piston of the vacuum pump. Thus, in many attempts to make such a vaporization system, the piston would "freeze" to the side walls of the cylinder. Attempts have been made to interject oil into the fuel, but this oil then was injected into the engine with the fuel vapor mixture causing unburned hydrocarbons from the oil and resulting in residue which was damaging to the engine.